Radio apparatus



Aug. 2 3, 1927.

RADIO APPARATUSl c o o o c c F. s. MccULLoVUGl-l a Sheets-Sheet 2 www m*Patented Aug. 243, 19.27.

UNITEDA -LsTATEs PATENT QFFICE."

FREDERICK s. MCCULLOUGH. 0E CLEVELAND, OHIO, AssIGNon To GLENN L.MARTIN,

or oLEvELAND, oHIo.

RADIO .APPARATUS Application filed. January 9, 1920. Serial No. 350,362.

My invention relates to radio apparatus, and particularly to that partof the apparatus which is designed to detect, amplify or transmit radiooscillations. The general object of the invention is to increase theeiiiciency of and simplify such apparatus.

My invention consists of means. hereinafter fully described andparticularly set forth in the claims,

This application is a continuation in part of my pending applicationSerial No. 128,375 iiled October 30, 1916, now issued as Patent No.1,403,700 of January v17, 1922, in so far as relates to that part of thesubject matter herein which'is common to both applications.

The annexed drawings and the following description set forth in'detailcertain means embodying my invention, the disclosed means, however,constituting but one of vari? ous forms in which the principle of theinvention may be used.

In said annexed drawings:

Fig. 1 is an explanatory diagram designed to illustrate the theoryunderlying the principle and the operation of my invention;

Fig. 2 represents a diagram ofl a simplel form of my radio apparatus;

Figs. 3, 4 and 5 represent modications'of 4apparatus employing theprinciple of my invention. i

Referring first to Fig. 1: 44 is a non# oXidizable heating filamentwhich may, as.

will hereinafter appear, be -kept at a certain predeterminedtemperature. In series with this filament is a battery 10 and rheostat 3connected by wires 41 and 57, the-temperature being adjusted by rheostat3. Surrounding this ilament 44 is an element 4'0 consisting ofsemi-dielectric material, such as glass. Surrounding this element 40 andin physical contact therewith is a control coil 45, which is connectedto the antennae 8 by the wire 9. The opposite end of'this coil is leftfree, .Surrounding the coil 45 is a second coil 455, which is in serieswith a seoond battery 56 and a rheostat 58. This latter coil surroundsand is in physical contact with a second tube 40, also consisting of asemi-dielectric material such as glass, and out of physical contactwiththe control coil. This coil is connected with the positive pole of asource 56 of power, herein shown to be a battery, the other pole beingconnected by means of wire 57 with one end of iilament 44, as shown.

When filament 44 is heated so that it will glow', it emits electrons.The coil 55, being connected in series 'with the battery 56, ,is alsoheated and this heat is transmitted to the glass tubes 40 and 40 whichit surrounds, thus placing them in a state of ionization. The glassthereby becomes conductive, rendering these glass tubes electrolytic andthe electrons pass therethrough as a result of such heating. and thecoil 55 being connected positively with the battery 56, the electronswill pass through the glass, which is an electrolyte, to coil 55. As aresult, current will flow from coil 55 to filament 44 in the oppositedirection from theI flow of electrons. That the current does so flow maybe shown by means of the ammeter A or other indicating device which maybe introduced into the circuit as shown in Fig. 1. l

When electromagnetic waves impinge on the antennaeS, passing along thewire 9 to control electrode 45, they will alter the iow ,of current fromcoil 55 to fila-ment 44, and this alteration will be indicated onamgmeter A.

This being the case,

This arrangement of parts, itwill also be noted, makes of the filament44 a cathode, and of the coil 55 an anode,- and the interposed coil 45 acontrol member. It must also be understood that the qg'ioil 55 is alsoa, local control member, for i'by raising or lowering the current flowin said coil, electrolytic action, i. e., the conductivity to velectronflow will be` increasedor decreased accordingly, and any iiuctuationswhich may resultyfrom said loca-.l control may then be noted on ammeterA, due to the consequent variation in the current in the filament circuit.

In Fig. 2 I have illustrated a modification of the. abovev describedapparatus also embodying the principles of my invention. IIn 0o- 7 5 and80-85, by means of which the current passing through the filamentdue tothe charge effect on the condensers may be regulated and the latterheated to the predeterlnined incandescence. By enclosing the filament inan evacuated tube, I am enabled` to increase this incandescence to agreater degree than if this filament were not en'- closed. In theinterior of the tube and adjacent to and interposed between the tubeswalls and the filament, is the control element 45 herein shown toconsist ofa fiat plate. This plate is connected in series with thepositive pole of the source of power 47,

herein shown to be a battery, the negative pole of this battery7 beingconnected with one end of thefilament by means of the wire 11.

Surrounding the exterior of the glass tub/eA 40 and preferably inphysical contact therewith is the heating coil 55, which is connected inseries with a source of power 5,6 herein shown to be a generator of highor radiofrequency currents. This high frequency generator producesalternating currents of frequencies corresponding to or approaching thefrequency of the circuit including generator 10, so that the coil willproduce in tube 40 an oscillating field of a frequency substantiallycoincident with the frequency of the received impulses impressed orinduced oncapacities75 and 85. The effect of this oscillating field isto heat the cathode and tube and io'nize the attenuated gas within thetube and to attract and repel the electron flow from the heated cathodetoward andfrom the walls of the vessel in a variable manner, in a directrelation to the oscillating frequency of the received impulses fromgenerator 10. In this circuit, also, is the rheostat; 58, by meansofwhich' the passage of current through the coil 55 may be regulated.

When current is passed through the filament '44 and the latter raised toincandescence, electrons are emitted and impinge the interior surfaceyof the tube or vessel 40.

yCurrent is simultaneously passed through the heating coil 55 so asto'raise the same to the required temperature.- This heating coil heatsthe latter and converts it to a state of ionization, thereby renderingit conductive, thus setting up an electrolytic action, the glass actingas an electrolyte. Current -is therefore thus permitted to pass from thec anode coil 55 to the cathode filament 44.

, The element 45 within the tube is the elec-I tron control; that is tosay, it modifies \the flow of electrons between the filament 44 and thecoil 55. This control may be eected by varying the potential ofthebattery 47, as shown, or by any other suitable means which will vary theconditions of the circuit containing the element 45. Any interactionbetween the circuit containing the anode 55l yand the filament 44 andthe circuit containing the control member would necessarily affect theconditions of the control due to the 40 is a surroundingevacuated glasstube,

55 being the ionizing means and the anode, surrounding tube 40 and invphysical con'- tact therewith. The tube 40l is provided to prevent theionizing means from'oxidizing. To regulate the current flow, rheostat 58is placed in series. This coil 55 is connected to the positive pole ofsource of power 56. lVithin this tube 40 is the incandescent lament 44.The source of power for making thisv filament incandescent is shownv tobe a generator -10 for exciting the oscillator. The variable condensers70-75 and 80-85 regulate the current. Interposed between this filamentand the coil 55 is the control mem-1 ber 45.. This control member leadsout of the tube 40 and is connected by a wire 12 to the inductance 20,and the center of this inductance is connected to the filament. .Theopposite end of this inductance 2O is connected through the ammeter A tothe negative side of the source of power 56. The tuning condensers 21and 22 show means for tuning these circuits. The condenser 23 isprovided to facilitate the stopping of audiofrequency :noises from thepower source 56. 86 and 87 are mica shields to prevent the stems 88 and89 from becoming ionized f which is very important in an electrolytedetube.. 44 is the filament, and 10 a source of power for making thefilament incandescent, 3 being a rheostat for regulating the currentflow. The condensers 24 and 25 have been included for purposes of tuning-and also the variable -inductance 20 introduced. The power for theanode circuit is derived from source 56 passing through impedances 26and 27 and across these the audio-frequency smoothing-.out condenser 23is placed. By this structure, anode 55 becomes an inductance and thecontrol 45 also an in- Condensers 24 and 25 are means for lvarying thefrequency of the oscillations in the respective circuits containing saidinductances. By the action of the inductances 55 and 45 `I am able tomake this device self-exciting.

stat 3. The action which takes place is `as poses.'

- doing, 'I

follows: .When filament 44 becomes incandescent, it will, as alreadydescribed, emit free electrons which impinge upon the inner wall of the,semi-dielectric tube 40 and would remain'there if this glasslike wallwere not placed in a state of ionization. The anode is connected to thepositive pole of' the source of power 56, to the inductance 29. This-inductance 29 is' so 'constructed as to lbe variable and to have aportion slide over the. tube 40 and to bring it to inductive relationwith coil 45. Across the inductancel 29 is placed` a condenser 30 fortuning pur- 'The opposite end of this inductance is connected to' thefilament 44 by wire 31. To facilitate further tuning, condenser' 24is'placed in series with the coil 45` and the negative side of source ofpower 56. By So obtain a powerful oscillator. To propagate theseoscillations, I attach to the coil 29 an antenna 8 and ground connection13 which runs to theifilament passing through ammeter A, thus placing ayload on the device so that it will radiate electromagnetic waves.

The principles of my invention, as will be understood by those skilledin the art, may be used in a detector, amplifier, oscillator, oroscillation generator.

. In every case, with the exception of Fi `l, the external coil is incircuit with a hig frequency generator, as in Fig. 2, or in aregenerative` circuit wherever radio fre- 'quency oscillations areimpressed on the coil, as in the other figures. These radio frequencyoscillations in the coil have an ionizing action on the residual'gasesinthe tube,

rendering the gas conductive and at the same.

Vtime this state of ionization of the gas, due

to the friction of the ions and molecules,

will raise the temperature of the glass envelope, ionizing it; that is,rendering it conductive, while also heating any metal parts tube. Wherethe circuit is organized as in Fig. 2, the inductive action of theoscillating field within the tube produced by coil 55 isthe principalmeans for heating cathode 44, as the charge effect on capacities 7 0-7 5and 80-85 would generally be insufficient to effect this, as is the casewhere the sending and receiving stations are -remotely located. In otherwords, the heating of the filament by the charge effect on thecapacities- -7 5 and 80-85 is incidental and normally negligible.

What I claim is: 1. In a radio apparatus, the combination of a filament,a glass-like wall surroundiilng I asaid filament, means for heating thementfmeans for heating the wall; said filament and heating meansconstituting electrodes of an electrical circuit.

-2. Ina radio apparatus,-thecombination of a sealed globe; a filamentwithin said globe; means for heating the filament; means Vfor heatingthe globe; and an electron control adjacent said filament within saidglobe; said filament and heating mea'ns constituting electrodes of anelectrical circuit.

3. In a radio apparatus, the combination ond electrode; and a micashield interposed between said filament and the end portion of saidglobe.

5. In radio apparatus, the combination of a partially evacuated globe; afilament within the globe; means for heating the filament; and meansoutside of the globe for heating said filament; said filament and saidglobe heating means constituting electrodes of an electric circuit. j

6. An electron valve comprisinga sealed conductor Ielements enteringopposite ends thereof; a lament within sai-d globe connected to saidconductor elements; an anode conductor outside said globe; and micashields interposed between said -filament and end portions of saidglobe.

7 The combination with a thermionic tube having an electron emittincathode therein` and having an attenuate gaseous content, an energyreceiving capacity incircuit with the cathode, a second electrode withinthe vessel, a local battery having one terminal .connected with saidelectrode and globe having one terminal in circuit with said cathode, acoil surrounding the tube,.and a local generator for impressing radiofrequency currents `on said coil, whereby said coil may cathode forefectingelectron emission therefrom.

9. The combination with v a thermionic tube having an emitting cathodetherein and having an attenuated gaseous content, of means for ionizingsaid gaseous content and heating the cathode to sustain electronemission therefrom comprising an external coil and a generator of radiofrequency oscillations in circuit with the coil.

10. The combination With an electron tube having a cathode therein andhaving an attenuated gaseous content, of aA coil sur rounding thecathode in inductive relation thereto, and a local generator of highfrequency currents in circuit with the coil, said 'coil and generator'constituting means for maintaining an oscillating field in the tube toeffect ionization of gases therein and effect heating of thecathode tosustain electron emission therefrom.

11. The method of heating a cathode to effect electron emissiontherefrom n an evacuated vessel n which there is 'a gaseous residuum bymeans vof a surrounding coil Whichlconsists in passing radio frequencycurrents through said coil and thereby produce an oscillating fieldWithin said vessel having suiicient energy to heat thefcathode whereuponelectron emission is effected.

Signed by me, this 29th day of December, 1919.

FREDERICK s. MCCULLOUGH.

